Method and apparatus for evaluating for the purpose of decoding a bitstream having a data structure fulfilling the requirements of two different data structure standards, and storage medium containing such bitstream

ABSTRACT

There are different types of DVD systems, e.g. the replay-only DVD-Video system and the re-recordable DVD-VR system. A DVD-VR type disc containing a DVD-VR type bitstream is to be replayed on a DVD-VR type recorder or player. However, it is also possible to record a DVD-Video type bitstream on a DVD-VR type disc in a DVD-VR type recorder, for replay of that disc in a DVD-Video type player. Because the DVD-VR and DVD-Video formats are different and contain different content they are not compatible with each other and a disc containing a bitstream of the one type can not be replayed on a player of the other type, a user must make a choice of which type of bitstream recording on a disc. One solution to this problem would be to record a separate disc for each type of bitstream. According to the invention a special type of bitstream is assembled and recorded on a disc that can be replayed on both types of players. This special type of bitstream is compatible with the DVD-Video system as well as the DVD-VR system. For both systems, corresponding additional files are added to their specific directories, but the resulting bitstream for both system types represents the same identical file on the disc. A disc containing a bitstream having such data structure can be replayed on both, DVD-VR and DVD-Video players.

This application claims the benefit under 35 U.S.C. 365 of InternationalApplication PCT/EP01/10619, filed Sep. 14, 2001, which claims thebenefit of European Patent Application No. 00250321.7, filed Sep. 27,2000.

The invention relates to a method and to an apparatus for evaluating forthe purpose of decoding a bitstream having a data structure fulfillingthe requirements of two different data structure standards, and relatesto a compatible storage medium containing such bitstream and to a methodfor compatibly assembling such bitstream.

BACKGROUND

There are different types of DVD (digital versatile disc) systems, forinstance the replay-only DVD-Video system and the re-recordable DVD-VRsystem. DVD-Video is specified in: DVD Specification for Read-Only Disc,Part 3, Video Specifications, Version 1.0, August 1996.

DVD-VR is specified in: DVD Specification for Rewritable/Re-recordableDiscs, Part 3, Video Recording, Version 1.0, September 1999.

The corresponding bitstreams have different formats and differentcontent.

WO-A-00 02195 discloses a DVD compatible with the DVD-Video standard andthe DVD-RTR standard. The contents data is stored in separatedirectories and files.

EP-A-0 944 087 shows a DVD containing audio/video information and audioinformation, wherein for each type of player different navigationinformation is recorded for the same object.

INVENTION

A DVD-VR type disc containing a DVD-VR type bitstream is to be replayedon a DVD-VR type recorder or player. However, it is also possible torecord a DVD-video type bitstream on a DVD-VR type disc in a DVD-VR typerecorder, for replay of that disc in a DVD-Video type player.

Because the DVD-VR and DVD-Video formats are not compatible with eachother and a disc containing a bitstream of the one type can not bereplayed on a player of the other type, a user must make a choice ofwhich type of bitstream recording on a disc.

One solution to this problem would be to record a separate disc for eachtype of bitstream.

The problem to be solved by the invention is to make the requiredprocessing easier in order to free a user from the decision about whichtype of bitstream is to be recorded. This problem is solved by themethod disclosed in claim 1. An apparatus that utilises this method isdisclosed in claim 7. A storage medium containing a correspondingbitstream is disclosed in claim 11.

According to the invention a special type of bitstream is assembled andrecorded on a disc that can be replayed on both types of players. Thisspecial type of bitstream is compatible with the DVD-Video system aswell as the DVD-VR system. The reason for this compatibility is that theheader of a data pack contains an information about the type of datacontained in the payload of the pack. A data type unusable for, orunknown to, a specific type of player is not evaluated by that type ofplayer. For both systems, corresponding additional files are added totheir specific directories, but the resulting bitstream for both systemtypes represents the same identical file on the disc.

A disc containing a bitstream having the inventive data structure can bereplayed by both, DVD-VR and DVD-Video players. Even first-generationDVD players can replay such discs.

In principle, the inventive method is suited for evaluating for thepurpose of decoding a bitstream having a data structure fulfilling therequirements of a first data structure standard, the data of whichbitstream include first main overhead data and multiple data units, eachdata unit containing first data unit overhead data according to saidfirst data structure standard and encoded video data and encoded ornon-encoded audio data, wherein:

-   -   said bitstream additionally includes second main overhead data        such that said data structure of said bitstream fulfills also        the requirements of a second data structure standard that is        different from said first data structure standard;    -   said data units additionally contain second data unit overhead        data according to said second data structure standard;    -   said encoded video data and said encoded or non-encoded audio        data are common to said first and second data structure        standards;    -   when inputting said bitstream to a device operating on the basis        of said first data structure standard, evaluating said first        main overhead data and said first data unit overhead data of        said data units, and decoding said encoded video data and        decoding or processing, respectively, said encoded or        non-encoded audio data, but not evaluating said second main        overhead data and said second data unit overhead data of said        multiple data units, or    -   when inputting said bitstream to a device operating on the basis        of said second data structure standard, evaluating said second        main overhead data and said second data unit overhead data of        said data units, and decoding said encoded video data and        decoding or processing, respectively, said encoded or        non-encoded audio data, but not evaluating said first main        overhead data and said first data unit overhead data of said        multiple data units.

Advantageous additional embodiments of the inventive method aredisclosed in the respective dependent claims.

In principle the inventive apparatus is suited for evaluating for thepurpose of decoding a bitstream having a data structure fulfilling therequirements of a first data structure standard, the data of whichbitstream include first main overhead data and multiple data units, eachdata unit containing first data unit overhead data according to saidfirst data structure standard and encoded video data and encoded ornon-encoded audio data, wherein said apparatus operates on the basis ofsaid first data structure standard and wherein:

-   -   said bitstream additionally includes second main overhead data        such that said data structure of said bitstream fulfills also        the requirements of a second data structure standard that is        different from said first data structure standard;    -   said data units additionally contain second data unit overhead        data according to said second data structure standard;    -   said encoded video data and said encoded or non-encoded audio        data are common to said first and second data structure        standards, and wherein said apparatus includes:    -   means for inputting said bitstream;    -   means for evaluating said first main overhead data and said        first data unit overhead data of said data units, and for        decoding said encoded video data and decoding or processing,        respectively, said encoded or non-encoded audio data, but not        evaluating said second main overhead data and said second data        unit overhead data of said multiple data units.

Either, the first data structure standard can be the DVD-Video standardand the second data structure standard the DVD_VR standard, or, thefirst data structure standard can be the DVD_VR standard and the seconddata structure standard the DVD-Video standard.

Advantageous additional embodiments of the inventive apparatus aredisclosed in the respective dependent claims.

DRAWINGS

Exemplary embodiments of the invention are described with reference tothe accompanying drawings, which show in:

FIG. 1 inventive data structure for a DVD-VR disc storing DVD-Video andDVD-VR data;

FIG. 2 structure of a bitstream on a disc according to FIG. 1;

FIG. 3 different structure of a bitstream for a disc according to FIG.1;

FIG. 4 simplified block diagram of a DVD-Video or DVD-VR player.

EXEMPLARY EMBODIMENTS

As shown in FIG. 1, following Lead_In and File_Systems_Data twoadditional directories are inserted into the DVD-VR/Video rootdirectory: VIDEO_TS for DVD-Video and DVD_RTAV for DVD-VR.

All necessary files for the two systems are generated:

-   -   for DVD-VR_MAGR.IFO, VR_MAGR.BUP, VR_AUDIO.VRO;    -   for DVD-Video_TS.IFO, VIDEO_TS.BUP and possibly VIDEO_TS.VOB.

However, the kernel AV stream (audio/video stream) that is described bythe files VTS_xx_y.VOB for the DVD-Video system and VR_MOVIE.VRO andVR_STILL.VRO for the DVD-VR system, is the same bitstream, i.e.physically the DVD-Video and DVD-VR bitstreams are by only one stream.

To provide such feature the bitstream must have specific properties.Some of these properties are compelling, other properties are optional.

A corresponding bitstream structure as depicted in FIG. 2 is optimisedwith respect to compatibility with DVD-Video and DVD-VR. FIG. 2 showsthat the DVD-VR video object units (VOBU) are shifted with respect tothe DVD-Video object units: DVD-Video object units begin with anavigation pack NV_PCK whereas DVD-VR video object units end with anavigation pack NV_PCK that represents the beginning of the nextDVD-Video object unit.

A navigation pack NV_PCK is followed by a real-time data informationpack RDI_PCK, several video packs V_PCK, several subpicture packsSP_PCK, and several audio packs A_PCK. NV_PCK is used by DVD-Video only,RDI_PCK is used by DVD-VR only, V_PCK and SP_PCK and A_PCK are commonlyused by DVD-Video and DVD-VR.

Mandatory properties are:

-   a) Navigation Packs NV_PCK must point in the stream to the beginning    of each VOBU according to the DVD-Video standard, Part 3, Chapters    2.4.47, 4.6 and 5.2.2.-   b) Real-time Data Information Packs RDI_PCK must point in the stream    to the beginning of each VOBU according to the DVD-VR standard, Part    3, Chapters 2.4 and 5.4.4.-   c) The MPEG Video stream must have such values for horizontal_size    only that are allowed for DVD-Video as-well as for DVD-VR: 720, 704    and 352, but not 480 and 544 that are allowed in DVD-VR only, see    DVD-Video standard, Part 3, Chapter 5.4.1.2 and DVD-VR standard,    Part 3, Chapter 5.5.1.2.-   d) In case an audio stream is to be accepted under DVD-VR for Still    Picture (e.g. menus), it must have the stream number ‘1’. In case an    audio stream is to be accepted under DVD-VR for normal video (i.e.    not Still Picture), it must have the stream number ‘0’ to keep    compatibility with DVD-VR, see DVD-Video, Part 3, Chapter 5.2.4 and    DVD-VR, Part 3, Chapter 5.3.3.-   e) For Linear Audio streams (PCM streams) ‘0’ and ‘1’,    quantisation_word_length=00b (16 bits) is to be used only to keep    compatibility with DVD-VR, see DVD-Video, Part 3, Table 5.2.4-1,    Note 8 and DVD-VR, Part 3, Table 5.3.3-1, Note 8.-   f) For Linear Audio streams (PCM streams) ‘0’ and ‘1’,    audio_sampling_frequency=00b (48 kHz) is to be used only to keep    compatibility with DVD-VR, see DVD-Video, Part 3, Table 5.2.4-1,    Note 9 and DVD-VR, Part 3, Table 5.3.3-1, Note 9.-   g) To allow for DVD-Video and DVD-VR the common use of streams ‘0’    or ‘1’ for Linear Audio, only the values 0000b (mono) and 0001b    (stereo) can be used for number_of_audio_channels, see DVD-Video,    Part 3, Table 5.2.4-1, Note 10 and DVD-VR, Part 3, Table 5.3.3-1,    Note 10. Alternatively, if for DVD-Video only PCM audio streams    having a stream number greater ‘1’ are used, then also the value    1001b (dual mono) for number_of_audio_channels of linear audio    streams ‘0’ or ‘1’ can be used.-   h) If a subpicture stream is to be handled under DVD-VR as well as    DVD-Video, then it must have the stream number ‘0’ to keep    compatibility with DVD-VR, see DVD-Video, Part 3, Chapter 5.2.5 and    DVD-VR, Part 3, Chapter 5.3.4.

From a) and b) it follows that no DVD-Video VOBU exists that starts withthe same sector as a DVD-VR VOBU. Correspondingly, the same is true foreach DVD-VR VOBU. Besides this, there exist sectors NV_PCK in the streamthat are used only from a DVD-Video system and sectors RDI_PCK that areused only from a DVD-VR system, as mentioned above.

Optional properties are:

-   A) The use of audio streams having stream numbers >1. Such audio    streams can be decoded by DVD-Video players only and may therefore    fully match the DVD-Video standard specification, i.e. there is no    limitation of allowed features due to DVD-VR requirements.-   B) The use of subpictures having stream numbers >1. Subpicture    streams having a stream number >0 can be decoded according to the    DVD-Video standard only.-   C) The use of audio streams having stream numbers >1. More than one    audio stream may exist. However, audio stream numbers ‘0’ and ‘1’    must not co-exist in parallel in a DVD-VR VOBU in order to avoid    conflicts with DVD-VR.-   D) For Linear Audio (PCM) streams having stream numbers >1, the    parameters quantization_word_length, audio_sampling_frequency and    number_of_audio_channels may correspond to all possible values given    in the DVD-Video standard DVD-VR. There is no limitation    of-allowed-values due to DVD-VR requirements.-   E) For audio streams having a stream numbers >1 all audio formats    are allowed that are supported by the DVD-Video standard, e.g. DTS    coding format. There is no limitation due to DVD-VR requirements.-   F) The MPEG Video stream may use for horizontal_size the values 480    and 544 that are allowed for DVD-VR, if the corresponding video    packs are used by DVD-VR VOBUs only, but not by DVD-Video VOBUs, see    DVD-Video specification, Part 3, Chapter 5.4.1.2 and DVD-VR    specification, Part 3, Chapter 5.5.1.2.-   G) In user_data( ) fields in the picture layer of video streams    teletext information corresponding to the DVD-VR specification may    be contained. Such user data fields could contain for example    subpicture information, the content of which subpicture information    would be identical with the content of a second subpicture stream.

The bitstream structure depicted in FIG. 3 is more complex than thatdepicted in FIG. 2. In the VOBUs there are several additional subpictureand audio packs assigned to further stream numbers ‘1’ to ‘4’. However,only the subpicture and audio packs that are assigned to stream ‘0’ areused by a DVD-VR device. This specific bitstream structure is lesscompatible with DVD-VR, but emphasises the specific features ofDVD-Video and DVD-VR.

In a further embodiment of the invention the kernel AV stream contains,beside the above described part common to DVD-VR and DVD-Video, aspecific part or specific parts that are used for DVD-VR and DVD-Videoonly and to which the corresponding root directories, i.e. said first orsecond main overhead data, facilitate access.

FIG. 4 shows an optical disk D, which is driven by a motor M and fromwhich data are read by means of a pick-up P. These data are fed inconditioned form, for example after amplification and error correction,to a track buffer TB via an input DMA (direct memory access) controllerIDMA. The data are stored in buffer TB in order to compensate forinstantaneous or short-term data rate variations. The correspondingpartial data streams of the buffer-stored data stream are recopied fromthe track buffer TB in each case into an associated decoder: a videodecoder VID for MPEG video data, an audio decoder AUD for MPEG or AC3audio data, and a subpicture decoder for subpicture data. Such decodersrequire a dedicated bit buffer in order to access specific data in aspecific order at specific time instants. Therefore, the data for a datadecoder must be available in the output data stream in a combinationand/or order that possibly differs from the input data stream. Sincecurrent device architectures may demand a decoder bit buffer comprisinga single coherent memory area, the data initially stored in the trackbuffer can be re-copied into the bit buffer for the respective decoderby means of an output DMA controller ODMA in the required order and atthe required time instant. IDMA, ODMA and other stages can be controlledby a common processor μP or by separate processors. In a DVD-VR playerthe subpicture decoder may be replaced by a teletext decoder. A DVD-VRrecorder will additionally include corresponding video, audio andteletext encoders and means for writing encoded bitstream data on discD.

The bitstream can be stored for example on a DVD-RAM or DVD-RW or DVD+RWor DVD-R or DVD-ROM disc, or can have the corresponding format.

Instead of a DVD disc, any other storage medium can be used. It is alsopossible to send a bitstream according to the inventive data structurefrom a transmitter to a receiver, which decodes the received bitstreamaccording to one or the other DVD system type.

A further feature is to decode such received or replayed bitstreamsaccording to both DVD system types, thereby using the particularfeatures of the DVD-Video format, e.g. of having up to 32 sub-pictures,together with the particular features of the DVD-VR format, e.g.teletext.

1. Method of assembling a decodable bitstream having a data structurefulfilling the requirements of a first data structure standard, the dataof which bitstream include first main overhead data (VIDEO_TS) andmultiple data units (DVD_Video VOBU, DVD_VR VOBU), each data unitcontaining first data unit overhead data (NV_PCK) according to saidfirst data structure standard and encoded video data (V_PCK) and encodedor non-encoded audio data (A_PCK), wherein: said bitstream additionallyincludes second main overhead data (DVD_RTAV) such that said datastructure of said bitstream fulfils also the requirements of a seconddata structure standard that is different from said first data structurestandard; said data units (VOBU) additionally contain second data unitoverhead data (RDI_PCK) according to said second data structurestandard; said encoded video data (V_PCK) and said encoded ornon-encoded audio data (A_PCK) are common to said first and second datastructure standards.
 2. Method according to claim 1, wherein said firstdata structure standard is the DVD-Video standard and said second datastructure standard is the DVD-VR standard.
 3. Method according to claim1, wherein said data units (DVD_Video VOBU, DVD VR VOBU) additionallycontain subpictute data (SP_PCK) that are common to said first andsecond data structure standards, which subpicture data can be evaluatedand processed in devices operating on the basis of said first or on thebasis of said second data structure standards.
 4. Method according toclaim 3, wherein said data units (DVD_Video VOBU, DVD_VR VOBU) containadditional encoded audio data and additional subpicture datacorresponding to only said first data structure standard, whichadditional data can be evaluated and decoded or processed, respectively,only in said device operating on the basis of said first data structurestandard.
 5. Method according to claim 1, wherein said bitstreamcontains, beside said common encoded video data (V_PCK) and said commonencoded or non-encoded audio data (A_PCK), a specific part or specificparts that correspond to said first or second data structure standard,respectively, to which specific part or parts only said first or secondmain overhead data, respectively, facilitate access.
 6. Method accordingto claim 1, wherein said bitstream is stored on an optical disc (D), forexample a DVD-RAM or DVD-RW or DVD+RW or DVD-R or DVD-ROM disc.